MANGEMENT OF SENILE CATARACT
Cataract extraction is done only after evaluation of the retinal condition, then optical correction of aphakia has to be done.
I. Evaluation of the case:-
This is very important to avoid complications and to know if surgery is hopeful or not.
A. Preoperative examination of the eye:-
- The ocular surface (eyelids, conjunctiva and cornea) should be free from infections and other diseases.
- Examination of the anterior chamber, iris and pupil is done to exclude diseases that will affect the outcome of surgery as uveitis.
- Measure the IOP to exclude glaucoma.
B. Evaluation of retina and optic nerve functions:-
1. Subjective evaluation:-
a. Visual acuity should be matching with the density of cataract. It should be at least HM or PL with very dense cataract. No PL means damage of the retina or optic nerve (hopeless surgery).
b. Normal colour perception (assessment of macular function).
c. Light projection test: It is done in cases of mature cataract for assessment of the visual field. The patient is asked to fix his eye to his own finger in a dark room. A focused low intensity light is presented to his eye from 50 cm distance from various directions. The patient should identify the correct direction of light even with a very dense cataract. Bad light projection means unhealthy retina or optic nerve and poor surgical prognosis.
2. Objective evaluation:-
a Fundus examination if the cataract is not dense.
b. Ultrasonography: The A-scan is used to measure the antero-posterior diameter of the eye for IOL power calculation. The B-scan gives two dimensional image of the eye to show diseases as retinal detachment or vitreous hemorrhage.
c. The pupil should react normally to light.
d. Electrophysiolgical investigations:
* Electroretinogram (ERG) is used to evaluate the outer retinal layers.
* Visual evoked potential (VEP) is used to evaluate the conduction through the optic nerve.
II. Surgical techniques:-
A. Indications and timing of operation:-
1. To improve vision:-
- In IMSC and NC we interfere when cataract is dense enough to interfere with patient's activities.
- In MSC and HMSC we interfere without delay for fear of complications.
- We start by the more advanced eye because it is more liable for complications.
- If both eyes have mature cataract we wait few days between both eyes for fear of endophthalmitis.
2. Emergency treatment of lens induced glaucoma in cases of:-
- Phacolytic glaucoma (mention).
- Phacomorphic glaucoma (mention).
- Lens subluxaion, anterior dislocation or posterior dislocation (mention).
B. Choice of operation:-
- If the zonule is intact we do ECCE or phaco-emulsification.
- If there is subluxation or dislocation we do ICCE.